What does David Tennant have to do with Trick or Treat 2? The Doctor Who star is featured in the new series. His website explains that:

David has been doing a bit of time travelling with the help of magician Derren Brown. He was fooled into thinking he could see into the past and future for a stunt on the new series of Trick Or Treat.

Derren swooped after hiding in David’s make-up truck, on the set of Doctor Who, he said: "David's the only person who has ever screamed when I surprised them. But he reacted well to the trick, which used visualisation and suggestion techniques. He seemed to enjoy it."